1. Field of the Invention
The present invention relates to organosilane- and/or organosiloxane-containing agents for modifying the surface of fillers and includes their use for preparing filled polyamide compounds. The present invention further relates to surface-modified fillers, to polyamides filled therewith and to products produced on this basis.
2. Background of the Invention
It is known that fillers can be incorporated into polymers. One motive for doing this is cost saving. Some of the expensive polymer can be replaced by low cost extending filler. A further reason is the controlled modification of mechanical properties of the polymer. The filler then becomes a functional filler. This method can give a lasting improvement in the mechanical properties, such as tensile strength and flexural strength, of filled polyamide compounds, for example (referred to below as PA compounds).
Use has long been made of aminosilanes, e.g. DYNASYLAN(copyright) AMEO, to obtain relatively high filler levels (U.S. Pat. No. 3,843,591, EP 0136 540 B1). The disadvantage is the poor toughness of PA compounds prepared using aminopropyltrialkoxysilane. A typical PA compound comprises two completely different base components: an inorganic mineral and an organic polymer. The inorganic mineral is generally hydrophilic and has an ionic structure. The organic polymer is usually rather hydrophobic and has a covalent structure. The two base components have different coefficients of expansion, surface tensions, flexural strengths, etc. The greatest incompatibility is found at the interface between the inorganic and organic components. This is usually the point of weakness in a filled PA compound. Modifying the interface with aminoalkoxysilanes gives rise to a bonding bridge and thus to an increase in the strength of the PA compound. Although the aminosilane improves many mechanical properties, this does not apply to impact resistance properties.
Water-based compositions for specific amino-functional silicon compounds, inter alia those known as xe2x80x9cbisaminosilanesxe2x80x9d are disclosed in German Patent Application 199 08 636.2, and these can be used, for example, for modifying the surfaces of glass fibers or mineral fibers, and also for the surface modification or treatment of pigments.
EP 0 518 057 B1 discloses mixtures of vinyl-/alkyl-/alkoxy-containing siloxanes, used as crosslinking agents for thermoplastic polyolefins. Mixtures of aminopropyl-/alkoxy-/alkyl-functional siloxane oligomers are disclosed in German Patent Application 198 49 308.8, where the mixtures are used, inter alia, as coupling agents in filled thermoplastic compounds, in the coating of glass fibers, or else for silanizing fillers or pigments.
Water-based organopolysiloxane-containing compositions are disclosed in European Patent Applications EP 0 716 127 A2, EP 0 716 128 A2 and EP 0 832 911 A1, and these are essentially obtainable by mixing water-soluble aminoalkylalkoxysilanes and, if desired, glycidic-ether- or else methacryloxy-alkylalkoxysilanes with non-water-soluble alkylsilanes followed by acid catalyzed hydrolysis or, respectively, cocondensation with removal of the alcohol of hydrolysis. Compositions of this type, too, can be used for coating glass fibers, or else for silanizing fillers or pigments.
German Patent Application 198 18 923.0 relates to stable compositions of water-soluble amino- and alkenyl-functional organosiloxanes, and to the preparation of these and their use for modifying the properties of pigments or fillers, such as aluminum oxide, magnesium oxide, silica, chalk, gypsum, borites, glass fibers, glass beads, carbon black, wollastonite, kaolin, mica or talcxe2x80x94to name just a few examples.
German Patent Application 198 18 924.9 moreover teaches a process for preparing surface-modified fillers by way of treatment with an organosiloxane-containing composition, where, besides OH groups, the organosiloxane has at least one amino-functional group and, if desired, other functional groups selected from the group consisting of alkyl, haloalkyl, alkenyl, glycidyl ether alkyl, acryloxyalkyl and methacryloxyalkyl. Fillers of this type are used in adhesives, sealing compounds, polymer compounds, paints and surface coatings.
German Patent Application 198 30 128.6 relates to flame retardants whose surface has been modified by treatment with organosilanes and, respectively, with organosiloxanes. Flame retardants of this type are used, inter alia, in polyamides.
DE 199 29 021.0 describes the use of functional organyloranyloxysilanes or cocondensates of these on carriers in cable compounds.
An object of the present invention is to provide another way of preparing polyamides which are filled, strong and impact-resistant.
It has been found that in particular fillers which have been treated with an agent A, B or C, these being specified in greater detail below, give good strength properties together with good impact resistance properties in filled, and in particular kaolin-filled, PA compounds.
In a manner which is surprising and advantageous, good or improved impact resistance in the filled polyamide can be brought about with substantial retention of good strength properties by simultaneous modification of the interface between filler and polyamide (PA) with a component having adhesion-promoting properties, for example an aminosilane, and with a component having lubricant properties, for example an alkylsilane or a polyethersilane or a wax based on polyethylene (PE), polypropylene or silicone.
Agglomerate-free dispersion of the filler in the PA polymer matrix is essential, and this is achieved in a highly satisfactory manner by the use of fillers which are treated with one of the above agents.
Said PA compounds moreover have improved rheology and are therefore easier to compound. This implies further cost savings for the compounder.
The present invention provides organosilane- and/or organosiloxane-containing agents A, B and/or C for modifying the surface of fillers which are used in preparing filled polyamide.
Agent A comprises at least one amino-functional silicon compound of the general formula I
Rxe2x80x94NHxe2x80x94(CH2)3xe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(I)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and R is a linear or branched alkyl group having from 1 to 20 carbon atoms, a cycloalkyl group having from 5 to 12 carbon atoms or an aryl group having from 6 to 12 carbon atoms, preferably 3-[N-butylamino]propyltrimethoxysilane, 3-[N-butylamino]propyltriethoxysilane, 3-[N-cyclohexylamino]propyltrimethoxy-silane, or at least one compound known as a xe2x80x9cbisaminosilanexe2x80x9d, preferably xe2x80x9cBis-AMEOxe2x80x9d: [(H5C2O)3Si(CH2)3NH(CH2)3Si(OC2H5)3] or xe2x80x9cBis-AMMOxe2x80x9d: [(H3CO)3Si(CH2)3NH(CH2)3Si(OCH3)3], or at least one tertiary aminosilane, such as xe2x80x9cTris-AMEOxe2x80x9d: [(H3CO)3Si(CH2)3]3N, or a mixture made from primary and secondary and/or tertiary aminosilanes and/or aminosiloxanes which are obtainable by hydrolysis, condensation or cocondensation of primary, secondary and/or tertiary aminosilanes, where the average degree of oligomerization of the aminosiloxanes is from 2 to 20.
Agent B comprises i) at least one amino-functional silicon compound of the general formula II
Rxe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(II)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and R is an amino group of the formula H2Nxe2x80x94[(CH2)2NH]y(CH2)3, where y is 0, 1 or 2, preferably 3-aminopropyltrimethoxysilane (AMMO):[H2N(CH2)3Si(OCH3)3], 3-aminopropyltriethoxysilane (AMEO):[H2N(CH2)3Si(OC2H5)3], N-aminoethyl-3-aminopropyltrimethoxysilane (DAMO): [H2N(CH2)2NH(CH2)3Si(OCH3)3], or N-aminoethyl-Nxe2x80x2-aminoethyl-3-aminopropyltrimethoxysilane (TRIAMO): [H2N(CH2)2NH(CH2)2NH(CH2)3Si(OCH3)3], and/or comprises at least one secondary aminosilane, and/or comprises at least one tertiary aminosilane, and comprises ii) at least one alkyl-functional silicon compound of the general formula III
Rxe2x80x2xe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(III)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and Rxe2x80x2 is a linear or branched or cyclic, if desired fluorine-substituted, alkyl group having from 1 to 16 carbon atoms, or comprises at least one alkenyl functional silicon compound of the general formula IV
CH2xe2x95x90CHxe2x80x94(CH2)nxe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(IV)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and n is an integer from 0 to 20, or comprises a polyether-functional silicon compound of the general formula V
Rxe2x80x94(Oxe2x80x94CH2xe2x80x94CHRxe2x80x2)nxe2x80x94Oxe2x80x94(CH2)mxe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(V)
in which the groups Z are identical or different, Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, R is a linear or branched alkyl group having from 1 to 4 carbon atoms, Rxe2x80x2 is a hydrogen atom or a CH3 group, n is an integer from 5 to 20, m is 2 or 3 and x is 0 or 1, and/or if desired, comprises iii) a content of siloxanes which are obtainable by hydrolysis, condensation or cocondensation of compounds of the general formula II, of the secondary aminosilanesxe2x80x94cf. the general formula Ixe2x80x94, of the tertiary aminosilanes, compounds of the general formula III, IV or V, where the average degree of oligomerization of the siloxanes is from 2 to 20.
Agent C comprises i) at least one alkyl-functional silicon compound of the general formula III
Rxe2x80x2xe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(III)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and Rxe2x80x2 is a linear or branched or cyclic, if desired fluorine-substituted, alkyl group having from 1 to 16 carbon atoms, and comprises ii) at least one alkenyl-functional silicon compound of the general formula IV
CH2xe2x95x90CHxe2x80x94(CH2)nxe2x80x94Si(CH3)x(Z)3xe2x88x92xxe2x80x83xe2x80x83(IV)
in which the groups Z are identical or different and Z is an alkoxy group having from 1 to 3 carbon atoms or a hydroxyl group or a chlorine atom, x is 0 or 1 and n is an integer from 0 to 20, and/or comprises, if desired, iii) a content of siloxanes which are obtainable by hydrolysis, condensation or cocondensation of compounds of the general formulae III and IV, where the average degree of oligomerization of the siloxanes is from 2 to 20.
A particular series of secondary amines are compounds known as bisaminosilanes, such as bis-AMMO and bis-AMEO, and also the N-alkylated aminosilanes of the general formula I, preferably 3-(N-butyl-amino)propyltrimethoxysilane (DYNASYLAN(copyright) 1189).
For the purposes of the present invention, bisaminosilanes include those disclosed in DE 199 08 636.2, which also discloses a method for the hydrolysis, condensation or, respectively, cocondensation of primary and secondary aminosilanes. DE 199 08 636.2 also has examples of aminosiloxanes. The entire content of this reference and those listed below is expressly incorporated as part of the disclosure of the present application.
Examples of primary aminosilanes suitable for the present invention are 3-aminopropyltrimethoxysilane (AMMO), 3-aminopropyltriethoxysilane (AMEO), and N-aminoethyl-3-aminopropyltrimethoxysilane (DAMO).
An example of a tertiary aminosilane is [(H3CO3Si(CH2)3]3N (tris-AMEO).
Mixtures made from primary and secondary and/or tertiary aminosilanes and/or from aminosiloxanes may generally be prepared by adding each of the individual components while mixing thoroughly.
Agents A preferably comprise at least one aminosilane of the general formula II and at least one secondary aminosilane. Particular preference is given to agents with a content of AMEO or AMMO and from  greater than 0 to  less than 100% by weight of bis-AMEO or bis-AMMO as further active component.
Examples of alkylsilanes of formula III are the following compounds: methyltrimethoxysilane (MTMS), methyltriethoxysilane (MTES), ethyltrimethoxysilane (ETMS), ethyltriethoxysilane (ETES), n-propyltrimethoxysilane (PTMO), n-propyltriethoxysilane (PTEO), and octyltriethoxysilane (OCTEO).
Examples of alkenyl-functional silicon compounds of formula IV are: vinyltrimethoxysilane (VTMO), vinyltriethoxysilane (VTEO), and allyltrimethoxysilane.
An example of a polyether-functional silicon compound of formula V which may be used is DYNASYLAN(copyright) 4140, a trimethoxysilyl derivative of a polyethylene glycol.
Examples of other siloxanes for the purposes of the present invention, which are generally obtainable by hydrolysis, condensation or cocondensation of compounds of the formula I or II, or else compounds of the general formula III, IV or, respectively, V, and methods for the preparation of corresponding siloxanes are disclosed, in particular, in European Patents EP 0 518 057 B1, EP 0 716 127 A2, EP 0 716 128 A2, EP 0 832 911 A1, or else in German Patent Application 198 49 308.8. Examples of products included in this group are oligomeric propyltriethoxysilane (VPS 9892), oligomeric vinyltrimethoxysilane (DYNASYLAN(copyright) 6490) and cooligomeric alkyl/vinylsilane (DYNASYLAN(copyright) 6598).
A suitable method for the purposes of the present invention is to use agents B in which i) an aminosilane of the general formula II and ii) at least one alkylsilane of the general formula III or a polyethersilane of the general formula V are present as components, particularly preferably a mixture made from AMEO and MTES or a mixture made from AMEO and DYNASYLAN(copyright) 4140.
Preference is also given to agents B in which i) an aminosilane of the general formula II and iii) oligomers of at least one alkylsilane of the general formula III are present as components, for example a mixture of AMEO and a condensate based on PTEO.
For the purposes of the present invention preference is also given to agents B in which i) an aminosilane of the general formula II and ii) at least one alkenylsilane of the general formula IV are present as components, or in which i) an aminosilane of the general formula II and iii) oligomers of at least one alkenylsilane of the general formula IV are present as components, or in which iii) cooligomers of at least one aminosilane of the general formula II and at least one alkylsilane of the general formula III are present as components, or in which iii) cooligomers of at least one aminosilane of the general formula II and at least one alkenylsilane of the general formula IV are present as components.
For the purposes of the present invention, preference is also given to agents C in which i) an alkylsilane of the general formula III and ii) at least one alkenylsilane of the general formula IV are present as components, and/or which are composed of a cooligomer of components i) and ii).
According to the invention, agent A, B or C is used for the treatment of fillers, where these are in particular used for preparing PA compounds.
The fillers may generally be surface-treated with agent A, B or C by combining the fillers and agent, allowing these to interact, if desired with an increase in temperature, and, if desired, then heat-treating the fillers treated in this way once they have been isolated. The process may in particular be carried out as described in DE 198 18 924.9, and reference is made to DE 198 18 923.0 and DE 198 30 128.6.
The fillers preferably used for the present invention are glass fibers, glass beads, wollastonite, calcined kaolin, mica, talc, magnesium hydroxide, melamine cyanurate, montmorillonite or nanocomposites.
The present invention therefore provides the use of an agent A, B or C for the treatment of fillers, in particular those which are used in preparing filled polyamide.
The present invention also provides surface-modified fillers obtained according to the invention.
The present invention also provides products which comprise at least one filler treated according to the invention, in particular the product known as filled polyamide.
All parts set forth are parts by weight unless otherwise indicated.
Non-exclusive examples of polyamides which may be used in the present invention are those of nylon-6 type (poly-e-caprolactam), nylon-6,6 type (polycondensate made form hexamethylenediamine and adipic acid) or nylon-12 type (poly-12-dodecalactam). An example of commercially available nylon-6,6 is given by the ZYTEL(copyright) product group from DuPont. However, other polyamides may also be filled with the novel fillers.
Suitable amounts of a novel filler to be used in preparing a filled PA compound are from 0.1 to 70% by weight, preferably from 10 to 40% by weight.
A filled PA compound is generally prepared by mixing the polyamide and the coated filler in a compounding kneader. For this, two sets of metering equipment are used to add firstly polyamide pellets and secondly the filler to a mixer heated above the melting point of the polyamide, so that the desired degree of filling can be complied with. The degree of filling generally means the relationship by weight between polyamide and filler, e.g. if there are 60 parts by weight of polyamide and 40 parts by weight of filler in the compound the degree of filling is 40%. The PA compound coming from the mixer is then generally pelletized and may, for example, be injection molded to give semifinished or finished products.
Examples of products ready for use and produced, for example, by injection molding are a wide variety of housings for electrical devices and parts for motor vehicles, e.g. wheel caps and fan housings, to mention just a few.
The filled PA compounds obtainable according to the invention generally have good strength together with good impact resistance.
The present invention therefore also provides polyamide filled according to the invention, and also products based on a polyamide of this type.